The present invention relates in general to techniques for forming a pattern on a work piece, and in particular to an apparatus and a method for patterning a work piece using a computer-controlled reticle.
It is known in the current art to build precision generators using projection of spatial light modulators (SLMs) of the micro mirror type (U.S. Pat. No. 5,296,891) and WO 99/45439 of one of the same applicants as in the present application which is hereby incorporated by reference. Other types of SLMs include deflecting micro mirror devices, grating light valves, silicon light valves and liquid crystal modulators. Some relay light by reflection and others by transmission. To use an SLM in a pattern generator has a number of advantages compared to more wide-spread methods of using scanning laser spots due to the fact that the SLM is a massively parallel device and the number of pixels that can be written per second is extremely high. Compared to some types of scanners, in particular electro optic and accustom optic ones, a micro mirror SLM can be used at shorter wavelengths since it is a purely reflective device.
As the dimension of individual lines on the work piece and the separation thereof decreases the techniques for forming said pattern on said work piece have to be refined in order to meet the requirements of said pattern, such as for example the optimization of the lateral resolution and uniformity of the patterned lines over the work piece etc. Therefore, there is a need in the art for a method and an apparatus for the fabrication of said pattern on said work piece which fulfill these requirements.
In view of the foregoing background, the apparatus and method of the present invention of the present invention are useful to provide a pattern on a work piece with a line width below 1 mm, in many cases below 0.2 mm and in the foreseeable future below 50 nm. It is an object of the present invention to provide an improved apparatus and method for patterning a work piece. In a first embodiment, one aspect of the invention provides an apparatus for patterning a work piece arranged at an image plane and sensitive to electromagnetic radiation. Said apparatus may comprise a source emitting electromagnetic radiation directed onto an object plane, a computer-controlled reticle comprising a plurality of object pixels, adapted to receive said electromagnetic radiation at said object plane and to relay said electromagnetic radiation toward said work piece and an optical projection system comprising a Fourier filter adapted to filter said relayed radiation in a Fourier space and a first lens arrangement adapted to project essentially parallel central axes of cones of radiation onto said image plane. Other embodiments and aspects of the present invention are described in below and set forth in the claims.